Unions representing Tube train drivers will meet on Saturday to discuss the latest pay offer from London Underground.

The company has proposed an extra 0.5 per cent on top of the existing two per cent increase, backdated to 1 April.

It hopes to avoid industrial action which would cripple the network and cause further frustration for commuters struggling to beat the long-running Railtrack-RMT dispute.

Last Friday, LUL conceded the increase after meeting representatives from the RMT and the drivers' union Aslef at the headquarters of Acas, the

conciliation service .

The unions were hoping for substantially more than two-and-a-half per cent, but an LUL spokeswoman said on Monday it would be impossible to offer any more because the company 'just could not afford it'.

She said LUL wanted to 'avoid a strike which would help no one - its customers, its staff or the company', adding that it needed to find an extra pounds 48m to reduce its train operating costs by the start of the next financial year. The 0.5 per cent increase will mean an extra pounds 119 for train drivers who earn pounds 23,812 a year.

LUL said the offer was conditional on the strike threat being withdrawn. However, an Aslef representative said the ballot would go ahead as planned and that the threat of strike action was still 'very much alive'.